This invention relates to the field of treatment of toxic gases, and provides a method and apparatus for rendering toxic gases harmless before they are discharged into the atmosphere.
The present invention comprises an improvement over the scrubber described in U.S. Pat. No. 5,185,016, the specification of which is incorporated by reference herein.
Many industrial plants produce toxic gases which may not be legally discharged into the atmosphere without treatment. One example of such a toxic gas is HCl gas, which is a by-product of electronics fabrication processes. The present invention can be used to scrub HCl gas, as well as a wide variety of other toxic gases.
The scrubber in the above-cited patent includes a generally cylindrical rotatable member, surrounded by a non-moving stator disposed around the periphery of the rotatable member. The waste gas and the scrubbing liquid meet in the annular region between the rotatable member and the stator, and the scrubbing occurs in that region.
While the scrubber in the above-cited patent does perform its intended function, it also has certain disadvantages. Because the scrubbing in the patented device occurs only in a relatively small annular region, the device must occupy a large volume relative to the volume within which scrubbing actually occurs. Thus, the major portion of the volume of the patent device is wasted, since the interior region of the cylindrical rotatable member is not used for scrubbing. Thus, the throughput of the device is limited by the amount of gas and liquid that can be accommodated in a relatively small annular region. The efficiency of the scrubbing process is therefore limited, and one must expend relatively large amounts of energy to achieve the desired result. Also, with the device of the prior art, for a given flow rate of waste gas, one needs a relatively bulky and heavy machine, and one which consumes large amounts of energy.
The present invention overcomes the above-described disadvantages, by providing a scrubber having a much greater efficiency than the device of the prior art. The scrubber of the present invention consumes comparatively little energy, in relation to the flow rate of waste gas being treated. The present invention provides a method and apparatus in which the waste gas stream is efficiently mixed with a scrubbing medium, such as water, so that the toxic material in the gas stream is readily absorbed or encapsulated by the scrubbing medium.